1. Field of the Invention
The present invention relates to an image recording apparatus and an abnormal recording element determination method, and more particularly to a technology for determining a state of recording elements in an image recording apparatus which records images onto a recording medium.
2. Description of the Related Art
In recent years, inkjet recording apparatuses have come to be used widely as data output apparatuses for outputting images, documents, or the like. By driving recording elements, such as nozzles, provided in a recording head in accordance with data, an inkjet recording apparatus is able to form data onto a recording medium, such as a recording paper, by means of ink ejected from the nozzles.
If an abnormality has occurred in a recording element provided in the recording head, there is occurrence of a dot omission in which a dot that should have been formed is not formed, occurrence of a dot abnormality in which a dot of a different shape (and size) to the dot that should have been formed is formed, or occurrence of a dot position abnormality in which the position at which the dot is formed is displaced. In particular, if there is an abnormality in a particular recording element of a full line type recording head which has a row of recording elements (nozzle row) of a length corresponding to the printable width of the recording medium, banding aligned with the conveyance direction of the recording medium may appear in the recorded image, thereby causing the image quality to decline markedly.
In an image recording apparatus such as an inkjet recording apparatus, image quality is maintained by performing restoration of the recording elements and/or correcting dot abnormalities according to a result of rapidly determining abnormalities in recording elements.
One method for determining abnormalities in recording elements is known in which a test pattern formed on the recording medium is read in by means of a CCD or other sensors, and then the presence of an abnormality is determined by comparing the results read in with the test pattern data.
In a barcode recording apparatus disclosed in Japanese Patent Application Publication No. 2003-145734, a test pattern recorded by a recording head is read in by a scanner which is provided on the downstream side of the recording head, and defective nozzles identified from the read results are recorded in a recording device, thereby changing the image contents according to the recorded information.
In a recording apparatus disclosed in Japanese Patent Application Publication No. 6-297728, an ejection failure determination pattern is recorded on recording paper using ink ejected from ejection ports of a recording head, the recording density is determined by means of a photosensor, and any ejection ports producing ejection faults are identified according to the determination results.
In an image recording method, apparatus, recording material, and processed good thereof disclosed in Japanese Patent Application Publication No. 5-301427, during multi-pass printing by shuttle scanning, an image is read in by a sensor which reads in recorded images, and recording abnormalities are determined by comparing the read results with the print data so that compensation is made by altering the subsequent scanning or drive period in the multi-pass operation after the determining process.
However, in the barcode recording apparatus disclosed in Japanese Patent Application Publication No. 2003-145734 and the recording apparatus disclosed in Japanese Patent Application Publication No. 6-297728, a test pattern for determining abnormalities in the nozzles and ejection holes is required. When abnormalities in the recording elements are determined by using a test pattern, it is necessary to form a test pattern on a recording medium, thereby generating wasted recording medium. In addition, during the processes of forming and reading in the test pattern, the recording operation must be halted, so that the reproduction efficiency declines.
Furthermore, in the image recording method, apparatus, recording material, and processed good thereof disclosed in Japanese Patent Application Publication No. 5-301427, although a composition is adopted in this manner that the compensation is carried out in subsequent scans of the recording head when a recording fault is identified, it is not possible to correct recording faults in single-pass recording by means of a full line type recording head.